Nail Pseudomonas Infection
Pseudomonas nail infection, known clinically as green nail syndrome (chloronychia), is a bacterial infection of the space under the nail caused by Pseudomonas aeruginosa, an aerobic gram-negative bacterium that adapts well to and thrives in moist conditions.
Pseudomonas aeruginosa is an opportunist. It cannot invade a healthy nail plate while the nail's anatomical barrier is intact. Infection takes hold only when two conditions come together: a separated nail plate (onycholysis) or chronic inflammation of the nail folds (chronic paronychia), plus prolonged exposure to moisture.
- Where the Green Color Comes From:
- Pyocyanin: a green to blue-black pigment released outside the bacterial cell. It is the main pigment that turns the nail moss green, emerald or dark blue.
- Pyoverdine: a fluorescent yellow-green pigment that helps the bacteria scavenge iron from their surroundings to survive.
- Both pigments dissolve in water and alcohol, soak deep into the keratin layers of the nail plate and collect on the nail bed. Without proper medical treatment, the discoloration can persist even after the bacteria have been killed.
- The Role of Biofilm Under the Nail:
- Pseudomonas aeruginosa secretes exopolysaccharides that form a biofilm around its colonies in the gap under the lifted nail.
- This biofilm acts like protective armor, keeping ordinary antiseptic soaks and surface creams from reaching the bacteria. That is why the infection tends to return if you only soak your fingers at home.
Green nail syndrome is often misdiagnosed as a subungual hematoma, black fungal nail infection or, more worryingly, subungual melanoma. When non-specialist beauty clinics see a green-black nail, they often recommend removing the whole nail plate (nail avulsion), an invasive, painful procedure that can scar the nail bed and leave the nail looking poor for a long time. At Haute-Derma, every green-black nail is assessed under a Wood's lamp (365 nm) to confirm the cause, and treated with our nail-preserving protocol, without nail removal.
Clinical Features and Risk Factors
Main Risk Factors
- Wet work: surgeons, dentists, homemakers, car-wash workers, seafood processors, and spa or hair-salon staff.
- Regular artificial nails: frequent acrylic or gel nails. When an artificial nail starts lifting, water gets trapped between it and the natural nail, creating a damp "greenhouse" where P. aeruginosa multiplies easily.
- Existing nail damage: people with fungal nail infection (onychomycosis), nail psoriasis or nail separation after injury (traumatic onycholysis).
Clinical Features in Detail
- The classic triad:
- Green discoloration (chloronychia): streaks or patches of green, moss, olive or blue-black on the nail plate.
- Nail separation (onycholysis): the nail plate lifts off the nail bed at the free edge or the sides.
- Associated nail fold inflammation (paronychia): mild swelling of the surrounding folds, loss of the cuticle, and sometimes a little clear discharge.
- Pain: unlike Staphylococcus aureus infections, which throb painfully, Pseudomonas nail infection is usually painless or only slightly tender when the lifted area is pressed.
How Green Nail Syndrome Differs From Other Causes of Nail Discoloration
| Pseudomonas green nail | Black fungal nail (onychomycosis) | Subungual melanoma |
|---|---|---|
| Pseudomonas aeruginosa bacteria | Fungi (T. rubrum / Scytalidium) | Malignant change in pigment cells (melanocytes) |
| Moss green, green or blue-black | Yellow, brown, black or green-black, with thickening under the nail | Brown-black longitudinal band (melanonychia) |
| Yellow-green fluorescence under Wood's lamp | Negative (no fluorescence) | Negative (no fluorescence) |
| Spreads if the nail stays wet | Gradually spreads from the free edge toward the base; nail becomes thick and crumbly | Band widens and spreads onto the nail fold (Hutchinson's sign) |
| Medical debridement + Nd:YAG laser | Fungal testing + topical/oral antifungals | Urgent biopsy / Mohs surgery |
Our Medical Approach at Haute-Derma
At Haute-Derma, we treat Pseudomonas nail infections with a nail-preserving strategy (the Haute-Derma Non-Invasive Chloronychia Protocol), which clears the pigment and the bacteria without invasive nail removal.
Step 1: Light-Based Diagnosis and Onychoscopy
- Wood's lamp (365 nm): shows how far the fluorescent pyoverdine pigment has spread.
- High-magnification onychoscopy: examines the nail bed beneath the lifted plate to rule out small-vessel bleeding or a coexisting fungal infection.
Step 2: Medical Debridement and Biofilm Removal (Micro-debridement)
- Using a sterile medical burr, the dermatologist gently lifts away and trims the detached part of the nail plate (onycholysis).
- Nail bed cleaning: the sticky biofilm and pyocyanin deposits are removed from the nail bed, exposing the infected area to air (Pseudomonas is sensitive to dry air and is suppressed by it).
Step 3: Photothermal Disinfection With Long-Pulsed 1064 nm Nd:YAG Laser
- Targeted action: long-pulsed 1064 nm energy penetrates the nail bed and produces localized heat that denatures the cell-wall proteins of P. aeruginosa and breaks down pyocyanin molecules lodged deep in the keratin.
- Benefits: reaches bacteria in small crevices that antiseptic solutions struggle to get to, and stimulates local microcirculation to help the nail matrix grow a new nail plate.
Step 4: Targeted Antibacterial Delivery (TDD) and Barrier Repair
- The nail bed is irrigated with a biological antiseptic that shifts the surface pH, making the environment hostile to Pseudomonas.
- A drying serum is applied to help the nail bed re-attach to the nail plate.
- You will be shown how to keep the nail dry and protected from water during treatment, and asked to stop wearing artificial nails until the new nail has fully grown out.
